Background:
Relatively few studies have explored the relationship between air pollution and cause-specific mortality among hypertensive patients. This study evaluated whether short term exposures to nitrogen dioxide (NO2), ozone (O3), particulate matter <10 mm in diameter (PM10) were associated with higher risk of mortality among a large hypertensive patients.
Methods:
A total of 223,287 hypertensive patients who attended any public health-care services in Hong Kong and prescribed at least 1 antihypertensive agent for the first time between 2001 and 2005 were followed up until 2010. A time-stratified, bi-directional case-crossover design was adopted to study the association between environmental exposures and mortality outcomes.
Results:
For all-cause mortality, significant positive associations were observed for NO2 and PM10 at lag 0 to 3 days per 10 MIUg/m3 increase in concentration and the excess risks ranged from 1.187%- 2.501%. Significant positive associations were found for O3 at lag 1 and 2 days and the excess risks were 1.654% (95% C.I. 0.469%, 2.852%) and 1.207% (95% C.I. 0.025%, 2.404%), respectively. We found similarly positive associations between NO2 (excess risks: 1.786%-2.798%), PM10 (1.126%-1.847%), O3 (3.035%-3.355%) and mortality due to respiratory disease. In stratified analysis, these significant results were observed amongst those aged >65 years and in cold seasons only.
Conclusions:
Older hypertensive patients are susceptible to all-cause and respiratory disease-specific deaths from these air pollutants in cold weather. This implies urgent need for protective air pollution standards for this susceptible population.
Air Pollution and Respiratory Disease
